1. Field of the Invention
This invention relates to a ceramic material suitable for use in the casting and directional solidification of superalloys and, in particular, to a process for leaching the same from the casting.
2. Description of the Prior Art
The directional solidification of advanced superalloys, such as the eutectic superalloy NiTaC-13, requires casting times and temperatures beyond the capability of conventional silica based molds and cores. New mold and core materials must meet the basic criteria of chemical inertness to the molten alloy. The core, in addition to being chemically inert to the molten alloy, must also be capable of being easily removed from the casting by a method which does not adversely affect the engineering properties of the metal.
It is therefore an object of this invention to provide a material composition which is suitable for use as a core material in the casting and directional solidification of advanced superalloy material and is easily removed from the casting.
Another object of this invention is to provide a magnesia doped alumina ceramic material suitable for use in making cores for casting and directional solidification of advanced superalloys and which can be easily removed from the casting by a leaching process.
A further object of this invention is to provide a method for removing cores made of magnesia doped alumina from the castings of advanced superalloy material.